Genetic structure of a wide-spectrum chicken gene pool

The genetic structure of 65 chicken populations was studied using 29 simple sequence repeat loci. Six main clusters which corresponded to geographical origins and histories were identified: Brown Egg Layers; predominantly Broilers; native Chinese breeds or breeds with recent Asian origin; predominantly breeds of European derivation; a small cluster containing populations with no common history and populations that had breeding history with White Leghorn. Another group of populations that shared their genome with several clusters was defined as 'Multi-clusters'. Gallus gallus gallus (Multi-clusters), one of the subspecies of the Red Jungle Fowl, which was previously suggested to be one of the ancestors of the domesticated chicken, has almost no shared loci with European and White Egg layer populations. In a further sub-clustering of the populations, discrimination between all the 65 populations was possible, and relationships between each were suggested. The genetic variation between populations was found to account for about 34% of the total genetic variation, 11% of the variation being between clusters and 23% being between populations within clusters. The suggested clusters may assist in future studies of genetic aspects of the chicken gene pool.     

Activity of redox-regulatory systems in the tumor and surrounding tissues in various histological types of tumors

According to modern concepts, a malignant tumor is a complex dynamic system possessing numerous links with both the immediate environment and remote non-malignant tissues and organs. Changes in their redox balance can result in disruption of the normal tissue control. The aim of our study was to compare activity of enzymes influencing the redox state in the tumor tissue, peritumoral area, and nonmalignant tissues (taken by resection line) at various histological tumor variants. We found similar close level of reduced glutathione in the tissues of gastric adenocarcinoma and vulvar squamous cell carcinoma; however, dynamics of this parameter in the tumor surrounding tissues was different. In contrast to gastric adenocarcinoma, vulvar squamous cell carcinoma was characterized by a significant increase in glutathione content in the tumor tissue and increased activity of all investigated enzymes of the glutathione system in the tumor tissue and its peritumoral area as compared with the surrounding non-malignant tissue. These results underlie existence of clear differences in the functioning of the redox regulatory systems in the tumor and surrounding tissues of various histological origin and localization; these differences may be possibly attributed to different mechanisms involved in maintenance of the redox balance in the originally non-malignant tissues.     

Natural,semisynthetic and synthetic tyrosinase inhibitors

Tyrosinase plays a pivotal role in the synthesis of melanin pigment synthesis on skin utilizing tyrosine as a substrate. Melanin is responsible for the protection against harmful ultraviolet irradiation, which can cause significant pathological conditions, such as skin cancers. However, it can also create esthetic problems when accumulated as hyperpigmented spots. Various skin-whitening ingredients which inhibit tyrosinase activity have been identified. Some of them, especially ones with natural product origins, possess phenolic moiety and have been employed in cosmetic products. Semi-synthetic and synthetic inhibitors have also been developed under inspiration of the natural inhibitors yet some of which have no phenolic groups. In this review, tyrosinase inhibitors with natural, semi-synthetic and synthetic origins are listed up with their structures, activities and characteristics. Further, a recent report on the adverse effect of a natural melanin synthesis inhibitor which was included in skin-whitening cosmetics is also briefly discussed.     

Fine structure of the Gene's organ in the camel tick Hyalomma (Hyalomma) dromedarii (Ixodoidea: Ixodidae)

Gene's organ of the camel tick Hyalomma (Hyalomma) dromedarii is located in the anterodorsal region of the body cavity ventrad to the scutum. It consists of a short stalk, dividing posteriorly into 2 pairs of horns and then into tubular glands. In unfed ticks, the epithelial layer of both the stalk and horns is lined internally by 2 cuticular layers; an inner, thin, greatly folded, dense layer surrounds the organ main lumen, and an outer, thick, slightly folded, less dense layer abuts the cell apices. Only the inner cuticular layer extends into the horn posterior region and appears perforated with numerous pore canals and covered with fine, cuticular projections. The horn and tubular glands epithelium is structurally consistent with a secretory function that apparently increases as feeding progresses. During oviposition, the inner cuticular layer unfolds and inflates into a pair of balloonlike structures that evert through the organ external aperture to receive and manipulate each egg as it is laid, coating it with a waxy layer that prevents desiccation. The fine cuticular projections may have a function in gripping the eggs as they leave the vagina. This organ appears to be everted by hydrostatic pressure from the hemolymph and is retracted by muscles.     

Long-term memory modules

One particular kind of structure offers possible explanations, for long-term memory, efficient consolidation of stored information from the environment, clustering of data strings and multimodal functioning. It is a possible model for pieces of neural structure and its use offers a uniform method for both studying and constructing an extensive class of mechanisms.